Specifies dimensions and specific requirements for the 15-pole connector and its contact allocation to enable electrical connection between commercial towing vehicles and their trailers equipped with 24 V systems to be made and to ensure interchangeability. Further specifies a park socket used to receive and store the plug when it is disconnected. Annex A specifies characteristics of two adaptors to be used between a connector meeting the requirements of this standard and 7-pole connectors specified in ISO 1185 and ISO 3731.